1. Field of the Invention
The present invention relates to a housing for an axial flow heat-dissipating fan. In particular, the present invention relates to a housing for an axial flow heat-dissipating fan for increasing an inlet amount of air and for maintaining wind pressure inside the housing.
2. Description of Related Art
U.S. Pat. No. 6,132,171 discloses a blower that sucks air inside a wall through radial slits as a fan rotates. The wall is formed away from ends of fan blades. Outer peripheral sections of the wall are planar and substantially flush with a rectangular casing body at a middle of upper, lower, right, and left sides of the body. The radial slits are formed in the wall for increasing the air inlet amount. A plurality of annular plates are spaced from each other and stacked in a direction along an axis of rotation of the fan to form the wall with radial slits. Spacers forming and supporting the slits are arranged toward the middle of each of the four sides of the casing body and located on the outer peripheral sections. However, turbulence easily occurs when air is flowing through the area between the fan blades and the radial slits, as the airflow passing through the radial slits along a direction is almost orthogonal to the airflow passing through the air inlet.
U.S. Pat. No. 6,710,486 discloses a housing structure for a heat-dissipating fan. The housing structure comprises a housing, a plurality of axial guide blades, and a rotor. A radial air inlet is formed between two adjacent axial guide blades for increasing the inlet air amount. When the rotor is rotated, major airflow is sucked through an air inlet into the housing. Also, blades of the rotor change airflow sucked through the radial air inlets from a radial direction to the axial direction of the housing. Due to the additional airflow, airflow between the upstream and the downstream of the blades can be balanced and air noise is lowered. However, since each radial air inlet has a uniform width throughout its length, the airflow that has just left the air outlet may be sucked back into the housing at the area adjacent to the air outlet side when the airflow is being sucked by the rotor into the housing via the radial air inlets. The air output is thus adversely affected. Further, in a case that the radial air inlets are two wide, the air pressurizing effect in the housing is reduced, failing to provide expected blowing efficiency.